A highly directional speaker with amplitude-phase control using a digitally direct-driven system

The paper proposes a novel directive control method with amplitude-phase control for a beamforming speaker by using a digitally direct-driven system with an array loudspeaker. This system can achieve high directivity and control side-lobe attenuation with the amplitude-phase control. The output pulse width is controlled using pulse width modulation for changing the amplitude and phase by using several 1-bit D flip-flops be cause the subloudspeakers are driven by 1-bit digital signals without digital-to-analog controllers and amplifiers. A segmented noise shaping dynamic element matching method is used to reduce the noise generated by the mismatch of subloudspeakers, which degrades the signal-to-noise ratio. Simulation results show that the side-lobe level can be reduced by 11 dB in comparison to using a conventional phase control system and that the attenuation at an attenuation angle is 32 dB.